This invention relates to a curable impregnant composition for use in impregnating electrical appliances.
Electrical appliances such as condensers and transformers, have recently been earnestly required to have a higher voltage resistance, greater capacitance and smaller size than conventional ones. To meet these requirements, there have been proposed impregnation-type condensers and transformers prepared by being impregnated with an impregnant and then cured in order to improve their electric characteristics. Further, in connection with said requirements, a part or the entire amount of the insulating material or dielectric material such as insulating paper for electric appliances has been substituted by plastics.
Heretofore, styrene monomer which is one of aromatic olefins, has been used as an impregnant for electrical appliances. This monomer is impregnated together with a suitable curing agent such as an organic peroxide and is then cured for use. However, styrene monomer is not desirable as an impregnant for electrical appliances in which plastics are used as a dielectric or insulating material since it has disadvantages such as solubility to plastics.
Further, an unsaturated, styrene dimer having two aromatic rings, such as 1,4-diphenyl-butene-1, has been proposed to be used as one of the ingredients of an electrical insulating oil for impregnation (U.S. Pat. No. 4,347,169), however, it is used only for impregnation and is not cured when used.
Still further, British Pat. No. 855,004 discloses that diisopropenyl diphenylmethane or the like which is a diolefin having two aromatic rings is used as a crosslinking agent for polystyrene, however, this Patent discloses nothing about the use of such a diolefin as a curable impregnant, particularly a curable impregnant for electrical appliances.